Adjustable specimen holder for an electron microscope with heat conducting feathered leaf springs



Aprll 5, 1966 KARL-HEINZ HERRMANN ETAL 3,244,877

ADJUSTABLE SPECIMEN HOLDER FOR AN ELECTRON MICROSCOPE WITH HEATCONDUCTING FEATHERED LEAF SPRINGS Filed Feb. 19, 1962 2 Sheets-Sheet l 6'l ,2, 77 5 J///% E//////// Hi a \ JHHHHHHI \\\\\\\w MAM d 14/42 April5, 1966 ADJUSTABLE SPECIMEN HOLDER FOR AN ELECTRON MICROSCOPE WITH HEATCONDUCTING FEATHERED LEAF SPRINGS KARL-HE|NZ HERRMANN ETAL 3, 7

2. Sheets-Sheet 2 I N VEN TORS ZZ/A /Z//Z- 7 K ATTORNEYS United StatesPatent many Filed Feb. 19, 1962, Ser. No. 174,200 Claims priority,application7Germany, Feb. 28, 1961,

s tllaims. cl. zso-ias The invention disclosed herein is concerned withan electron microscope equipped with a specimen adjusting table which isnot supported symmetrically to the radiation axis, that is, which isadjustable by means of two drives which are arranged within themicroscope housing and which act perpendicularly one with respect to theother. Such specimen adjusting tables comprise basically the tableproper, which may be termed the table body, in which is arranged a conefor receiving the specimen cartridge, hereinafter briefly referred to asreceiving cone.

Undesired motions of the specimen occur disturbingly, especially in thecase of electron microscopes which are provided with means for heatingthe specimen, and also upon employing normal specimen cartridges, suchmotions being in the latter case caused by the heating of the table bodydue to the effect of the electron beam, resulting in heat expansion ofthe table. These specimen motions cease only when a thermal equilibriumis attained between the cartridge, the table and the microscope. Theattainment of the thermal equilibrium is in known constructions delayed,particularly as a result of the poor heat conductioin which existsbetween the table and the microscope.

The above indicated drawbacks are also observed in connection withelectron microscopes equipped with the known specimen adjusting tablesand provided with means for cooling the specimen.

The object of the present invention is to provide an electron microscopeequipped with a specimen adjusting table of the indicated kind, whereina thermal equilibrium between the cartridge, the table body and themicroscope, is quickly attained, thereby reducing the duration andextent of the specimen motions.

This object is, ccording to the invention, realized by the provision ofmeans for drawing oif heat from the specimen table, particularly fromthe receiving cone, to the microscope, which does not hinder theadjustability of the specimen adjusting table. Such means can beprovided, for example, in the form of flexible mechanical connections. Apreferred embodiment of the invention comprises a leaf spring whichconducts the heat well, and which is constructed feathered to form aplurality of relatively narrow spring fingers so as to provide for goodthermal contact with parts of the microscope.

This measure may be supported by arranging the receiving cone in heatinsulating manner in the table body. The heat conduction to the table,and therewith the temperature increase thereof which results in heatexpansion causing the motion of the specimen, is held as small aspossible, owing to the heat insulated arrangement of the specimencartridge and therewith of the receiving cone in which is arranged theheat source.

Since the specimen adjusting table is disposed within the vacuum spaceof the electron microscope, the heat insulation between the receivingcone and the table will be best when there is little direct of indirectconnection between these two parts which extends over other parts.

In order to construct this ideal case as best as possible, the receivingcone is in a preferred embodiment of the invention by means of screwssuspended in heat insulating relation in the table body. Upon using forthis purpose screws which are made of a heat insulating material, thereceiving cone will have practically no heat conducting connection withthe table body. The screws may be arranged so that they permitadjustment of the height of the receiving cone by moving it andtherewith the specimen cartridge relative to the table in the directionof the radiation axis.

In order to facilitate the centering of the receiving cone, which is inthe described manner suspended in heat insulating relation in the table,there may be provided ring shaped or bar shaped or punctiform webs whichare carried by and extend from the surface facing respectively the otherpart of the receiving cone and/or the table. In a preferred embodimentof this variant of the electron microscope according to the invention,the web is made of heat insulating material, thus also practicallyexcluding heat condition over these centering elements.

It will be understood that the effect of the above indicated measuresfor avoiding a temperature increase of the specimen table, which resultsin a disturbing specimen motion particularly in the case of a specimenadjusting table which is not symmetrically supported with respect to theradiation axis, can be supported by likewise heat insulating thespecimen cartridge with respect to the receiving cone therefor.

Further details of the invention will now be described with reference tothe accompanying drawing showing the parts of the embodiment of anelectron microscope which are of interest in connection therewith.

FIGS. 1 and 3 are sectional views;

FIG. 2 shows an elevational view; and

FIG. 4 schematically illustrates an electron microscope with portionsthereof broken away.

As will be seen particularly from FIGS. 1, and 3, the specimen adjustingtable comprises basically the table body 1 in which is arranged thereceiving cone 2 for the specimen cartridge ill. The table It is inknown manner equipped with rollers 3, 3 or the like, such rollerssupporting the table with respect to the drives d, d, non-symmetricallyto the radiation axis. This is the reason for the tendency of the tablebody 1, responsive to heating thereof, as a consequence of the heatingof the specimen cartridge and heat conduction over the receiving cone,to execute due to heat expansion motions relative to the radiation axis,thereby producing disturbing motions of the specimen.

In order to avoid these motions, there: are provided means which are toserve for the drawing oil of heat from the receiving cone to themicroscope. These means comprise leaf springs 5 and 6 which are in thisembodiment fastened to the receiving cone 2, the ends of these leafsprings which lie in engagement with the microscope proper beingfeathered. The advantage of such feathering of the leaf springs is, thata good heat contact is obtained even in the presence of irregularitiesin the corresponding engagement plane of the microscope.

In the illustrated embodiment, the receiving cone is arranged in thetable body 1 in heat insulating manner, by means of screws '7 and 8which also permit adjustment of the height of the receiving cone andtherewith corresponding position of the specimen.

The receiving cone 2, which is in this way in heat insulating mannersuspended by the screws which are preferably made of heat insulatingmaterial, is for the centering thereof provided with an annular or ringshaped web or rib 9, such rib having a small cross sectional area andlying in engagement with the table 1 only with a cor- (D respondinglysmall contact surface. It will be seen particularly from FIG. 1, thatthere is no other connection between the table body 1 and the receivingcone 2, so that the intermediate space between these parts is nearlycompletely formed by heat insulating vacuum. It will be realized thatthe annular rib may receive different form and that it need not be madeof metal but may form an independent part made of suitable heatinsulating material. Likewise, the specimen or object cartridge 10 maybe provided with similar ribs or webs 11.

The specimen cartridge (not shown) can be inserted in the describedspecimen adjustment table in heat insualting manner, thus resulting in aminimum heat conduction from the specimen, which may be heated bysuitable means provided in the cartridge, over the receiving cone 2 tothe table, thereby assuring quick attainment of the equilibrium betweenthe respective parts and the microscope.

FIG. 4 shows the arrangement of the specimen adjustment table providedaccording to the invention with means 5 and 6 for leading off heat fromthe table proper or body 1 of the electron microscope 4d. The tableproper in which is inserted the specimen or object cartridge lltl, issituated above the pole piece system 41 of the objective lens, whosewinding is designated by the numeral 42. The beam generation system ofthe apparatus is positioned above the table 1 and primarily cornprisesthe cathode 43, Wehnett cylinder 44 and the anode 45. The electron beamleaving this system is bundled in a condenser, the pole piecearrangement of which is designated by the numeral 46 and which has thetwo energizing coils 4'7 and 48.

The invention may also be advantageously used in connection with anelectron microscope provided with means for cooling the specimen. Athermal equilibrium will in such case likewise be attained very quickly.

Changes may be made within the scope and spirit of the appended claimswhich define what is believed to be ew and desired to have protected byLetters Patent.

We claim:

1. An electron microscope with a specimen adjustment table which issupported nonsymmetrically with respect to the radiation axis, saidtable comprising a table body, and a receiving cone arranged therein forreceiving a specimen cartridge, heat conducting feathered leaf springsoperatively extending between said table and the adjacent portion of themicroscope, for producing a heat-conducting connection between thespecimen adjusting table and the microscope, said springs beingconstructed to permit unrestricted adjustment ofthe specimen adjustmenttable.

2. An electron microscope according to claim 1, comprising means forarranging said receiving cone in heat insulating manner in said table.

3. An electron microscope according to claim 2, comprising screw meansmade of heat insulating material for suspending said receiving cone insaid table in heat insulating relation with respect thereto.

An electron microscope according to claim 3, wherein said screw meansare arranged so as to permit adjustmerit of the height of the receivingcone relative to the table body.

5. 'An electron microscope according to claim 4, comprising meansinterposed between said table and said receiving cone for centering thelatter in the table.

6. An electron microscope according to claim 5, wherein said centeringmeans is made of heat insulating material.

Reterences Cited by the Examiner UNITED STATES PATENTS 2,347,348 4/1944Young 250--49.5 2,380,209 7/1945 Bachrnan et al. 25049.5 2,728,84012/1955 Columbe 250--49.5 2,826,701 3/1958 Columbe 25049.5 2,845,5407/1958 Franken et a1. 250-49.5 2,858,444 10/195 Leisengang 250-495 RALPHG. NILSON, Primary-Examiner.

1. AN ELECTRON MICROSCOPE WITH A SPECIMEN ADJUSTMENT TABLE WHICH ISSUPPORTED NONSYMMETRICALLY WITH RESPECT TO THE RADIATION AXIS, SAIDTABLE COMPRISING A TABLE BODY, AND A RECEIVING CONE ARRANGED THEREIN FORRECEIVING A SPECIMEN CARTRIDGE, HEAT CONDUCTING FEATHERED LEAF SPRINGSOPERATIVELY EXTENDING BETWEEN SAID TABLE AND THE ADJACENT PORTION OF THEMICROSCOPE, FOR PRODUCING A HEAT-CONDUCTING CONNECTION BETWEEN THESPECIMENT ADJUSTING TABLE AND THE MICROSCOPE, SAID SPRINGS BEING CON-